Shark teeth:

In fifteenth-century Malta, tongue stones were suspended from decorative coral trees, called languiers, and used for dipping into wine to protect against deliberate poisoning. Languiers and other ornately mounted tongue stones were placed on side tables (Kredenzen) during banquets. Guests would select a tongue stone from the languier, immerse it in their wine and rest assured that they would not succumb to poisoning.

Fossil sharks' teeth mounted as amuletic pendants were also worn as necklaces or bracelets for their anti-poison powers. Others were mounted in base or precious metals and attached to silver or gold watch chains (Zammit-Maempel 1989).